---
title: 卷快照类
content_type: concept
weight: 61 # 置于卷快照章节后
---

<!-- overview -->

<!--
This document describes the concept of VolumeSnapshotClass in Kubernetes. Familiarity
with [volume snapshots](/docs/concepts/storage/volume-snapshots/) and
[storage classes](/docs/concepts/storage/storage-classes) is suggested.
-->
本文档描述了 Kubernetes 中 VolumeSnapshotClass 的概念。建议熟悉
[卷快照（Volume Snapshots）](/zh-cn/docs/concepts/storage/volume-snapshots/)和
[存储类（Storage Class）](/zh-cn/docs/concepts/storage/storage-classes)。


<!-- body -->

<!--
## Introduction

Just like StorageClass provides a way for administrators to describe the "classes"
of storage they offer when provisioning a volume, VolumeSnapshotClass provides a
way to describe the "classes" of storage when provisioning a volume snapshot.
-->
## 介绍 {#introduction}

就像 StorageClass 为管理员提供了一种在配置卷时描述存储“类”的方法，
VolumeSnapshotClass 提供了一种在配置卷快照时描述存储“类”的方法。

<!--
## The VolumeSnapshotClass Resource

Each VolumeSnapshotClass contains the fields `driver`, `deletionPolicy`, and `parameters`,
which are used when a VolumeSnapshot belonging to the class needs to be
dynamically provisioned.

The name of a VolumeSnapshotClass object is significant, and is how users can
request a particular class. Administrators set the name and other parameters
of a class when first creating VolumeSnapshotClass objects, and the objects cannot
be updated once they are created.

{{< note >}}
Installation of the CRDs is the responsibility of the Kubernetes distribution. 
Without the required CRDs present, the creation of a VolumeSnapshotClass fails.
{{< /note >}}

-->
## VolumeSnapshotClass 资源  {#the-volumesnapshortclass-resource}

每个 VolumeSnapshotClass 都包含 `driver`、`deletionPolicy` 和 `parameters` 字段，
在需要动态配置属于该类的 VolumeSnapshot 时使用。

VolumeSnapshotClass 对象的名称很重要，是用户可以请求特定类的方式。
管理员在首次创建 VolumeSnapshotClass 对象时设置类的名称和其他参数，
对象一旦创建就无法更新。

{{< note >}}
CRD 的安装是 Kubernetes 发行版的责任。 如果不存在所需的 CRD，则 VolumeSnapshotClass 的创建将失败。
{{< /note >}}

```yaml
apiVersion: snapshot.storage.k8s.io/v1
kind: VolumeSnapshotClass
metadata:
  name: csi-hostpath-snapclass
driver: hostpath.csi.k8s.io
deletionPolicy: Delete
parameters:
```

<!--
Administrators can specify a default VolumeSnapshotClass for VolumeSnapshots
that don't request any particular class to bind to by adding the
`snapshot.storage.kubernetes.io/is-default-class: "true"` annotation:
-->
管理员可以为未请求任何特定类绑定的 VolumeSnapshots 指定默认的 VolumeSnapshotClass，
方法是设置注解 `snapshot.storage.kubernetes.io/is-default-class: "true"`：

```yaml
apiVersion: snapshot.storage.k8s.io/v1
kind: VolumeSnapshotClass
metadata:
  name: csi-hostpath-snapclass
  annotations:
    snapshot.storage.kubernetes.io/is-default-class: "true"
driver: hostpath.csi.k8s.io
deletionPolicy: Delete
parameters:
```

<!--
If multiple CSI drivers exist, a default VolumeSnapshotClass can be specified
for each of them.
-->
如果存在多个 CSI 驱动程序，可以为每个驱动程序指定一个默认的 VolumeSnapshotClass。

<!--
### VolumeSnapshotClass dependencies

When you create a VolumeSnapshot without specifying a VolumeSnapshotClass, Kubernetes
automatically selects a default VolumeSnapshotClass that has a CSI driver matching
the CSI driver of the PVC’s StorageClass.

This behavior allows multiple default VolumeSnapshotClass objects to coexist in a cluster, as long as
each one is associated with a unique CSI driver.

Always ensure that there is only one default VolumeSnapshotClass for each CSI driver. If
multiple default VolumeSnapshotClass objects are created using the same CSI driver,
a VolumeSnapshot creation will fail because Kubernetes cannot determine which one to use.
-->
### VolumeSnapshotClass 依赖关系  {#volumesnapshotclass-dependencies}

当你创建一个 VolumeSnapshot 且未指定 VolumeSnapshotClass 时，
Kubernetes 会自动选择一个默认的 VolumeSnapshotClass，
该类与 PVC 的 StorageClass 所使用的 CSI 驱动程序匹配。

这种行为允许多个默认的 VolumeSnapshotClass 对象在集群中共存，
只要每个默认类都与唯一的 CSI 驱动程序进行关联。

请始终确保每个 CSI 驱动程序只有一个默认的 VolumeSnapshotClass。
如果使用相同的 CSI 驱动程序创建了多个默认的 VolumeSnapshotClass 对象，
则创建 VolumeSnapshot 时会失败，因为 Kubernetes 无法确定使用哪个类。

<!--
### Driver

Volume snapshot classes have a driver that determines what CSI volume plugin is
used for provisioning VolumeSnapshots. This field must be specified.
-->
### 驱动程序 {#driver}

卷快照类有一个驱动程序，用于确定配置 VolumeSnapshot 的 CSI 卷插件。
此字段必须指定。

<!--
### DeletionPolicy

Volume snapshot classes have a [deletionPolicy](/docs/concepts/storage/volume-snapshots/#delete).
It enables you to configure what happens to a VolumeSnapshotContent when the VolumeSnapshot
object it is bound to is to be deleted. The deletionPolicy of a volume snapshot class can
either be `Retain` or `Delete`. This field must be specified.

If the deletionPolicy is `Delete`, then the underlying storage snapshot will be 
deleted along with the VolumeSnapshotContent object. If the deletionPolicy is `Retain`, 
then both the underlying snapshot and VolumeSnapshotContent remain.
-->
### 删除策略 {#deletion-policy}

卷快照类具有 [deletionPolicy](/zh-cn/docs/concepts/storage/volume-snapshots/#delete) 属性。
用户可以配置当所绑定的 VolumeSnapshot 对象将被删除时，如何处理 VolumeSnapshotContent 对象。
卷快照类的这个策略可以是 `Retain` 或者 `Delete`。这个策略字段必须指定。

如果删除策略是 `Delete`，那么底层的存储快照会和 VolumeSnapshotContent 对象
一起删除。如果删除策略是 `Retain`，那么底层快照和 VolumeSnapshotContent
对象都会被保留。

<!--
## Parameters

Volume snapshot classes have parameters that describe volume snapshots belonging to
the volume snapshot class. Different parameters may be accepted depending on the
`driver`.
-->
## 参数 {#parameters}

卷快照类具有描述属于该卷快照类的卷快照的参数，可根据 `driver` 接受不同的参数。